Angklung is a musical instrument from West Java, and has been recognized widely by the public in Indonesia. Physically, Angklung is a musical instrument made of bamboo trunk in which the sound is generated from air resonance due to the vibration at the internode of bamboo trunk. The size of the internode of bamboo trunk produces sound with a frequency that represents a particular tone. Therefore, an Angklung musical instrument usually is a series of several sections of bamboo internode to produce a variety of tones that covers the notes in a song.
An Angklung that represents a note usually consists of two sections of bamboo internode of different sizes in length but have the same kind of tone. The length is designed to determine the high and low tones. Thus, in general, an Angklung can produce sound of a note with a combination of high and low tone frequencies.
Angklung tones usually correspond the musical scales in general, ie. pentatonic and diatonic scales. Pentatonic scales consist of five notes per octave, whereas diatonic scales consist of seven notes in one octave. The addition of the octave, in principle, is a repetition of notes composition at each scale of note. Therefore, the number of Angklungs corresponds to the number of notes, both in diatonic and pentatonic scales, which are required to play a song. Generally the notes required are more than one octave.
Unfortunately, playing Angklung by a single player cannot produce musical sounds perfectly, especially to play three notes at the same time (chord). In order to play a song perfectly, more than one person or a group of Angklung players are required. In addition, to date there is no instrument that is able to play Angklung automatically and to replace the human role. Therefore, it is required to invent a device for playing an Angklung musical instrument automatically.